1. Field of the Invention
This invention relates to an improvement in pressure garments, examples of which are full and partial pressure suits, anti-G suits, torso counter pressure garments, etc. of the type worn by crew members in high performance high altitude aircraft and space vehicles.
2. Description of the Prior Art
The known pressure garments of the above-described type conventionally employ impervious, solid film or solid coating laminate materials for retention of gases under pressure. Examples of such materials include neoprene and urethane. While such materials are effective gas barriers, they are also effective water vapor barriers which inhibit natural dissipation of the wearer's metabolic heat output via perspiration evaporation. In order to offset the resulting discomfort and reduction in performance due to heat stress, in many cases it has become necessary to integrate complex and burdensome cooling systems into the pressure garments.
In the totally unrelated field of all-weather garments, it is known to employ flexible micro-porous materials of the type disclosed for example in U.S. Pat. No. 4,194,041 (Gore et al.) granted on Mar. 18, 1980. As described in this patent, the disclosure of which is incorporated herein by reference, such micro-porous materials include an interior hydrophilic layer and an exterior hydrophobic layer. The hydrophilic layer prevents flow of gases or liquids through open pore channels, but permits the transfer therethrough of substantial amounts of water by absorbing water on the side facing the wearer's body where there is a high concentration of water vapor, and desorbing or evaporating water on the opposite side where water vapor concentration is relatively lower. The exterior hydrophobic layer is porous and permeable to gases, but does not permit water to spread on its surface and wick into its porous structure. Such micro-porous materials have been employed extensively in a wide range of outer garments, including rainwear, windbreakers, jogging suits, etc.